Noncontact Mapping-Guided Catheter Ablation of Posterosuperior Right Atrial Tachycardia Associated with Sick Sinus Syndrome

Focal atrial tachycardia (AT) is sometimes associated with sick sinus syndrome. A 57-year-old female complained of palpitation, fatigue and presyncope. Ambulatory monitoring demonstrated frequent segments of AT and subsequent sinus arrests. P wave morphology of ectopic beats was similar to that of sinus rhythm. After obtaining diagnosis of bradycardia tachycardia syndrome, she underwent electrophysiologic study (EPS) and radiofrequency (RF) catheter ablation to eliminate AT. Conventional EPS could not be performed due to frequent spontaneous ectopic beats. EnSite mapping demonstrated that AT originates from posterosuperior right atrium (RA) and that local electrogram of ectopic focus precedes the onset of P wave in surface ECG by 40 msec. After EnSite-guided RF ablation to the target area, ambulatory monitoring detected no AT or sinus arrest. EPS performed one week after RF ablation showed atropine-induced partial restoration of sinus node dysfunction. Her symptoms were resolved remarkably and permanent pacemaker implantation has not been necessary to date. RF ablation guided by EnSite mapping was useful to eliminate AT arising from limited ectopic focus and this case implies existence of "pacemaker-avoidable" bradycardia tachycardia syndrome.